They sell them at a deli in Southwold, Suffolk (where I often go on holiday), but that's (generally!) a fair distance to go for one! :p They also (used) to sell them at Mr. Scruff's place in Manchester (just opposite Al Faisal), but didn't seem to when I went in there just before Christmas...

Thanks Nick, and just to answer the hundreds of emails I've had on the subject, I had the steak with irish stout pie and served it with mashed potato, cauliflower, broccoli, carrots and gravy, hope this helps